Functional groups have been introduced into aldose and ketose saccharide molecules through the formation of acetals or ketals. The reaction of a reducing saccharide at the aldose or ketose moiety with an alcohol results in the formation of an acetal or ketal glycoside composed of two parts: one part is the residue of the saccharide, commonly referred to as the glycosyl moiety, and the other part is the residue of the alcohol, commonly referred to as the aglycone moiety. The glycoside can be useful as a polyol having much greater stability in the presence of alkaline materials than the corresponding reducing saccharide. The use of lipophilic alcohols to form the aglycone moiety of the glycoside can impart surface active properties to the glycoside.
U.S. Pat. Nos. 2,356,565 (Chwala) and 3,931,148 (Langdon) disclose reacting a halo-substituted alcohol with a reducing monosaccharide to form a glycoside having a halo-substituted aglycone moiety and then reacting the resulting glycoside with an organic compound, e.g. a fatty amine, to prepare a glycoside having a substituted aglycone moiety and that has surface-active properties.
U.S. Pat. No. 3,737,426 (Throckmorton) discloses surface-active glycosides prepared by the alcoholysis of starch with a polyol to form a glycoside having an hydroxyl-substituted aglycone and sequentially reacting the resulting glycoside with a short-chain epoxyalkane and a long-chain epoxyalkane.
U.S. Pat. No. 4,719,272 (Tsai et al.) discloses reacting a mono- or low molecular weight polysaccharide with a halohydrin or halo-alcohol to form a halohydrin or glycidyl glycoside and then reacting the resulting glycoside with an unsaturated amine to prepare a monomeric cationic glycoside.
The above methods all link a glycoside substituent to the aglycone moiety of the glycoside molecule rather than the glycosyl moiety by reacting a derivatizing agent with the glycoside. Accordingly, any reaction by-products of the derivatization must be separated from the glycoside itself. Further, the glycoside substituent is labile to cleavage from the molecule upon hydrolysis of the aglycone moiety from the glycoside.